Ex vivo biomechanical comparison of four Center of Rotation Angulation Based Leveling Osteotomy fixation methods.

Objective: To compare the strength of four constructs used to secure an osteotomy in a Center of Rotation Angulation (CORA)-Based Leveling Osteotomy (CBLO) in an ex vivo model.

Study Design: Ex vivo study.

Sample Population: Thirty-two canine tibiae from 17 skeletally mature cadavers weighing between 18 and 33.2 kg.

Methods: Thirty-two paired tibiae with patella and patellar tendon were collected. Each tibia was randomly allocated to a construct group: plate and pin (Plate), plate with countersink compression screw (HCS), plate with tension band (TB), or plate with HCS and TB (HCSTB). Samples were loaded by distraction until failure. The stiffness, yield load, and ultimate load were compared between each fixation method.

Results: No difference in stiffness of the constructs was detected between groups (p = .6937). Yield load for the HCSTB group (1211.06 N) was greater than the TB group (1016.41 N), the HCS group (907.20 N), and the Plate group (787.73 N) (p = .0069). The ultimate load for the HCSTB group (1387.82 N) was greater than the TB group (1076.36 N), HCS group (926.62 N), and the Plate group (774.35 N) (p = .0004).

Conclusions: CBLO fixation augmented with a TB and HCS provided a stronger construct that withstood a greater yield load and ultimate load than either augmentation strategy alone.

Clinical Significance: Augmenting a CBLO fixation with a TB and a HCS can provide increased construct strength.